In the past, a calendar date up to 99 was stored in a computer memory. The two base-ten digits were used to store calendar dates from (19)00 to (19)99, where the (19) was only implicitly understood.
In the present invention a hexadecimal date up to (20)65 can be stored in two four-bit memory blocks. The hexadecimal date is stored by means of a base-ten digit and a hexadecimal digit taken together, and by means of a hexadecimal digit and a base-ten digit taken together, and by means of two hexadecimal digits taken together. Two hexadecimal digits taken together can extend the hexadecimal date to FF. The stored hexadecimal date can reach past calendar year (19)99 to calendar year (20)65. A so-called xe2x80x9cyear 2000 problemxe2x80x9d can be put off for sixty five years by means of the present invention.
In the past, a two digit date used eight memory cells. Each memory cell is also known as a location, memory location or bit location. The eight memory cells would hold a base-ten number having two digits. Thus the date 99 would be supported by a memory block Z having eight bit locations Z1Z2Z3Z4Z5Z6Z7Z8. were Z1 etc. is a memory location.
In the past, the memory block Z contained binary values that went up to value 1001, to store a left digit of a two digit calendar date. Similarly the memory block Z contained binary values that went up to value 1001, to store a right digit of a two digit calendar date. Thus Z1Z2Z3Z4 only contained binary value up to 1001 while Z5Z6Z7Z8 only contained binary values up to 1001.
In the present invention, a binary value in left memory block X goes from 1001 to 1010 to 1011 to 1100 to 1101 to 1110, up to a binary value 1111. A final binary value in memory block  X is 1111. Thus X1X2X3X4=1111. That is, bit location X1, bit location X2, bit location X3 and bit location X4 of memory block X, taken together, can have binary values past 1001, up to the binary value 1111. This binary value corresponds to hexadecimal digit F. The left portion of a two digit hexadecimal date that exceeds date 99 can thus be expressed by using the hexadecimal digits A, B, C, D, E and F as well as the base-ten digit 9.
Also, in the present invention, a binary value in right memory block Y goes from 0110 up to a value of 1111. At this point Y1Y2Y3Y4=1111. That is, bit location Y1, bit location Y2, bit location Y3 and bit location Y4 of memory block Y, take together can have binary values from 0110 to 1111. Again this latter binary value corrsespondes to hexadecimal digit F. The right portion of the two digit hexadecimal date that exceeds date 99 can be express using the hexadecimal digits A, B, C, D, E and F as well as the base-ten digits 6, 7, 8, and 9.
The present invention includes a method for storing a hexadecimal date having two digits, the hexadecimal date beginning with 9A, comprising placing a four bit binary number having the value 1001 that corresponds to the base-ten digit 9 in a left memory block comprising four memory locations and placing a four bit binary number having a value corresponding to a hexadecimal digit selected from the group A, B, C, D, E and F in a right memory block comprising four memory locations.